Alloy.



outrun sraras PATENT OFFICE...

PERCY REXFORD PARSONS, OF LONDON, AND OS WALD SILBERRAD, F BUGKHURST HILL, ENGLAND.

I Patented Aug. 4, 1914.

ALLOY.

1,106,055. Specification of Letters Patent.

No Drawing.

To all Irh cm '1' 15 may concern:

lie 1t known that we, laucr REXl-ORD PAR- soxs, a subject of the King of Great Britain valso with the power which is exerted through the propeller. The difficulties of erosion arise both in very high speed vessels, such as torpedo boats, destroyers, and in high speed passenger vessels, battleships or cruisers, and becomes most serious when the present limits of speed are being approached.

This invention is based on the discovery that the capacity of metallic alloys to resist erosion is primarily dependent on the structure of the alloy, and that those alloys which have a structure essentially [5 or polyhedric in character withstand erosion far more effectively than those heretofore used.

\Ve wish it to be understood that the term erosion herein employed refers to mechanical abrasion or wear of the material as occurs under fluid friction as distinct from corrosion which is due to chemical orelectrochemical action.

The invention consists in the application of alloys which have a structure essentially [5 or polyhedric in character, and are preferably a homogeneous {5 solution, to the manufacture of high speed ship propellers, where "by propellers of much higher efficiency are obtained.

The desired {5 structure referred to consists generally as is well known of crystals in more or less close contact, usually of substantially uniform dimensions and of sub stantially the same crystalline character, whereas the alpha structure usual in the alloys heretofore employed consists generally of more or less widely separated acicular crystals in a. homogeneous matrix practically devoid of distinct structure.

Application filed March 25, 1910. 'Seria1 No. 551,535.

The beta or polyhcdric structure above referred to is possessed for example by an alloy composed of copper 54% and zino'ltifi. In an alloy of this kind having the desired structure we may substitute either the zinc or the copper by an equivalent quantity of many other metals, in order to insure the necessary mechanical strength in the prodnot, and still retain the desired structurefor example, 1 part of zinc may be replaced by any of the following metals, the amount of each of which is equivalentto 1 part of zinc approximately as stated below Slllcon 0.1 art rr Alumlnlunn. 0.16 co esponds appmlllmawly ii) 3 TIILH 0 u u u u u u u Lifld, L0 I H u u u u Cadml 7 Lo H u u u n u u -Iron 1.1 H u u u u Manganese 2.0 H u I u u 1 Similarly the copper may be replaced by suitable metals, for example, 1 part of copper is equivalent to 1.5 parts of nickel approximately. The amount of any metal made use of in replacing zinc or copper should not, however, be excessive, or the separation of some element or compound will occur, the presence of which will materially reduce the efficiency of the alloy in its capacity to withstand erosion-tl1us, the amount of silicon should not exceed about 1.4. Thus for best results the amount of tin should not exceed about 0.7 per cent, manganese should not exceed about 8 per cent, lead should not exceed about 1 per cent, cadmium should not exceed about 1 per cent. Further, two or more of the above metals may be' introduced into the same alloy providing the necessary equivalents be maintained; for example, the following is a Very Such an alloy possesses a structure very closely resembling a copper zinc alloy containing 5%.4- per cent. Cu a ud loli per cent. Zn.

Having now described our invention what we claim as new and desire to secure by Letters Patent is 1. An article intended to withstand erosive action in which the surface exposed to said action is formed of an alloy essentially (3 or polyhedric in structure; as set forth.

2. A ship s propeller in which at least the metallic surface exposed to erosive action is essentially of structure; as set forth.

3. A high speed ships propeller in which 5 at least. the metallic surface exposed to ero- 0 is formed of an alloy of beta structure composed at least principally of copper and zinc in such proportions as correspond to an alloy of substantially equal parts zinc and copper, as set forth. v

5. A high speed ships propeller in which at least the surface exposed to erosive action is formed of a copper-zinc alloy of (5 structure corresponding to a copper content of between 49 and 58 per cent; as set forth.

6. A high speed ships propeller blade, composed of an alloy essentially of beta structure as set forth.

7. A high speed ships propeller blade, containing about 54.6 parts of copper, about 43.13 parts of zinc, about 0.13 parts of manganese, about 1.44 parts of" iron, and about 0.70 parts of tin: as set forth.

'8. A high speed ships propeller blade composed of a copper zinc alloy of beta structure and having mechanical strength imparted thereto by addition of other.

' metal; as set forth.

744%, and in which 1,1oaoae 9. A high speed ships propeller blade composed of a copper zinc alloy of beta structure in which the copper and zinc are present in proportions equivalent respectively "to' between 49 and 56% and 51 and imparted to the material by substitution of either metal in part by other metal; as set forth. p 10. A propeller blade composed of a copper zinc alloy of-beta structure, in which the copper and zinc are present in proportions equivalent respectively to between 49% and 56% and 51% and 44%, and in which mechanical strength is imparted to the material by substitution in part of both metals by other metal.

11. A propeller blade composed of copper mechanical. strength is zinc alloy of beta structure, in which the copper and zinc are present 1n proportions equivalent respectively to between 49% and 56% and 51% and 44%, and in which mechanical strength is imparted to the material by substitution in part of the zinc by other metal.

In testimony whereof we afix our signatures in presence of two witnesses.

PERCY REXFORD PARSUNS. OSWALD SILBERRAD. i/Vitnesses:

'l. H. Bms'row, B. H. I. MATTHEWS.

topics at thiln patent may he obtained flor are t -arts filth, by addreoatngthe @omznttatener e13 Eeotonts. Watimmten, t. 

